This invention relates to a method for manufacturing a throw-away hob having throw-away tips mounted on the side surfaces of a plurality of unit screw threads formed at the screw threads of a threaded body.
In the well known conventional manufacturing process for throw-away hobs, it has been very difficult to form or machine, with a high degree of precision, throw-away tip mounting seat surfaces on the screw threads of a threaded body or on a plurality of unit screw threads thereof. As a result, the accuracy of mounting throw-away tips was poor, thereby adversely influencing the accuracy of machining gears to be cut by the throw-away hob.
The machining accuracy obtained in the formation of throw-away hob mounting seat surfaces by the well known conventional machining work has been limited. Therefore, in late years, there have been devised a method of manufacturing a hob wherein seat surfaces are formed by machining by means of an end mill, and the like on a unit body having a row of peripherally extending threaded portions, whereupon throw-away tips are fitted to the seat surfaces, and another manufacturing method wherein a plurality of locaters are formed with seat surfaces by machining, and then the locaters are fitted in the peripheral surface of the hob body to provide a throw-away hob.
However, according to such recently developed manufacturing methods, the number of component parts of the hob and the number of machining operations have increased and the assembly operation has become troublesome, thus increasing the manufacturing cost thereof. Moreover, such manufacturing methods have a disadvantage that errors in the assembly result in a lower accuracy of mounting throw-away tips.